The present invention relates to Doppler Radar Systems and more particularly to a radar system for mounting on a vehicle to give an indication of the speed of such a vehicle.
There are particular problems where the speed of a slow moving vehicle requires to be assessed with accuracy. Previously known radars when mounted on such a vehicle produce inaccurate results due to the tilting and/or the vibration of the vehicle which affects the output of the Doppler radar which is attempting to measure the relative movement between the vehicle and the ground. In such cases it has been found more accurate to use a mechanical arrangement associated with the wheels of the vehicle but this has the disadvantage that where slipping of the wheels often occurs such as in the case of agricultural tractors an equally inaccurate speed measurement is produced. Where the speed measurement is used, for example to control the rate of application of a spray, this can lead to overspraying which can be extremely serious. Thus it is extremely important to be able to accurately measure the forward (or backward) speed of movement of a vehicle and the present invention seeks to provide for such a measurement.